why parpool only shows half of the processors

!nproc shows 56 where as parpool only 28. (more interesting: mapreduce function uses all aviable (56) workers and returns results for only half (28) - I am loosing half of my data GREAT.

Answer 1

[Walter Roberson]

The default 'local' pool is created only with the number of physical cores, not the total number of hyperthreads available, as using hyperthreading can reduce performance for computation. You can edit your 'local' pool configuration to change that.

Note: there have been reports that in virtualized systems, the detection algorithm might think there is only half the number of available processors.